Re: Programming a calendar system

I can't see how a week could be based on the number of planets visible,
since this is constantly changing. In one week,
you could have all the planets on view (at what time?) whereas two weeks
later a couple - Mercury and Venus, say,
could well have been lost from view. I'd always taken the week to be a
purely 'non-natural' construct, a good 'bridge'
between the units of a day and a month for those cultures that felt they
needed it.
Star masses (especially those on the main sequence) are confined within
fairly narrow limits, and the Sun makes a good
average. Stars with larger volumes have lower densities than the Sun, and
vice versa, so the mass M in Kepler's third law
works out to be roughly similar.
Mike
----- Original Message -----
From: "Nik Taylor" <yonjuuni@...>
To: <CONLANG@...>
Sent: Friday, April 30, 2004 6:07 AM
Subject: Re: Programming a calendar system


>
> Provided the mass of the sun is the same.  If you have an alien sun,
> then the mass would likely be different than ours, and the ratio
> wouldn't work.  Kepler's law is merely a simplification based on
> constant mass of the actual rotational period equation:
>
> P = SQRT((4pi^2*R^3/(MG))
>
> where P = period (measured in seconds) M is the mass of the sun
> (measured in kilograms; actually, technically, the total mass of both
> objects), R is the distance between the centers of the two objects
> (measured in meters), and G is the Gravitational Constant
> (6.67259*10^-11)
>
> Thus, if you have a constant mass (and the sun is so much more massive
> than any planet that the differences in M between different sun-planet
> pairs is negligible) it simplifies to a proportionality of OP =
> SQRT(R^3), i.e., T^2=R^3.  However, quadruple the mass, and keep the
> distance the same, and you'll halve the orbital period.
>
> > Sure, on Earth the size of the week was inspired by the number of
> > visible planets in the sky, and the size of the month by the phases of
> > our moon,
>
> For that matter, the 7-day week isn't even universal on Earth.  Very
> many cultures have weeks of other lenghts, such as 6 days in Japan, 8
> days in ancient Rome, 10 days in Egypt, 13 and 20 days among the maya,
> etc.

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